MONDAY, June 9, 2014 (HealthDay News) -- The majority of women with breast cancer get too little exercise for optimum health, a new study suggests.

After women are diagnosed with breast cancer, they are less likely to meet exercise recommendations that link physical activity with longer survival and better quality of life, researchers report online June 9 in the journal Cancer.

"Medical care providers should discuss the role physical activity plays in improving breast cancer outcomes with their patients, and strategies that may be successful in increasing physical activity among breast cancer patients need to be comprehensively evaluated and implemented," Brionna Hair, a doctoral candidate in epidemiology at the University of North Carolina at Chapel Hill, said in a journal news release.

American guidelines for physical activity state that adults should get at least 150 minutes of moderate exercise or 75 minutes of rigorous exercise every week to achieve any health benefit and to prevent or manage chronic health problems.

The researchers looked to see whether levels of physical activity among 1,735 North Carolina women with breast cancer changed after their diagnosis. The women, ranging from 20 to 74 years old, learned they had cancer between 2008 and 2011.

Researchers found that 59 percent reported getting less exercise six months after their diagnosis. On average, the women reduced their weekly level of activity by about five hours of brisk walking.

Just 35 percent of women treated for breast cancer met recommendations for physical activity after diagnosis, the study found.

After taking race into account, the study revealed that black women were about 40 percent less likely than white women to meet national physical activity guidelines after being diagnosed with cancer.

The study authors noted that black women die more often from breast cancer than other groups in the United States.